vi Testing Milk and Its Products. 



Chap. VI. THE LACTOMETER AND ITS APPLICATION . . . 100 



The Quevenne lactometer. Influence of temperature. 

 N. Y. Board of Health lactometer. Reading the lactome- 

 ter. Time of taking lactometer readings. Influence of solid 

 preservatives on lactometer readings. Cleaning lactometers. 

 Testing the accuracy of lactometers. Calculation of milk 

 solids. Adulteration of milk. Legal standards. The spe- 

 cific gravity of milk solids. Calculation of extent of adul- 

 teration: Skimming. Watering. Watering and skimming. 



Chap. VII. TESTING THE ACIDITY OF MILK AND CREAM . 117 



Cause of acidity in milk. Methods of testing acidity. 

 Manns 7 test. Devarda's acidimeter. The alkaline-tablet 

 test. Determination of acidity in sour cream. Spillman's 

 cylinder. The Marschall acid-test. Rapid estimation of the 

 acidity of apparently sweet milk and cream. Detection of 

 boracic-acid preservatives in milk. "Alkaline Tabs. " 



Chap. VIII. TESTING THE PURITY OF MILK 135 



The Wisconsin curd test. The fermentation test. The 

 Monrad rennet test. The Marschall rennet test. 



Chap. IX. TESTING MILK ON THE FARM 140 



Variations in milk of single cows. Number of tests re- 

 quired during a period of lactation in testing cows. When 

 to test a cow. Sampling milk of single cows. Composite 

 samples. Variations in herd milk. Influence of heavy grain 

 feeding and of pasture on the quality of milk. Method of 

 improving the quality of milk. 



Chap. X. COMPOSITE SAMPLES OF MILK 158 



Methods of taking composite samples. Use of tin dip- 

 per. Drip sample. The Scovell, McKay, and Michels' sam- 

 pling tubes. One-third sample pipette. Preservatives for 

 composite samples. Care of composite samples. Fallacy 

 of averaging percentages. A patron 's dilemma. 



Chap. XI. CREAM TESTING AT CREAMERIES 175 



The space system. The oil-test churn. The Babcock test 

 for cream. Gathering and sampling hand-separator cream. 

 Chap. XII. CALCULATION OF BUTTER- AND CHEESE YIELD . 186 



A. Calculation of yield of butter: Butter-fat test and 

 yield of butter. Variations in composition of butter. Over- 

 run of churn over test. Factors influencing the overrun for 

 milk and for cream. Calculation of milk and cream over- 

 run. Conversion factor for butter fat. Butter yield from 

 milk of different richness. Use of butter chart. Use of 

 overrun table. 



B. Calculation of yield of cheese: From fat. From sol- 

 ids not fat and fat. From casein and fat. 



